Add POST method to /v1/library/<dummy> redirect route

[formed2forge]

ANONYMIZED_KOBOPLUSPurchase-DefaultCWA-250219-1509h39.log
Adding POST method to /v1/library/ redirect implementation allows for syncing of notebooks on pen-enabled devices.

EDIT 1: Upon reverting the change, syncing of notebooks persists. I'm missing something...

EDIT 2: This change also fixes an issue where clicking "Read with Kobo Plus" silently fails to add a Kobo Plus book to a users account from the Kobo Store on device. (Device tested: Libra Colour). The following log is relevant to the error that lead me to open this PR.

Feb 19 15:09:44 nickel: (  1826.473 @ 0x2571038 / packetdump.debug) -------------------------- REQUEST --------------------------- 
Feb 19 15:09:44 nickel: (  1826.473 @ 0x2571038 / packetdump.debug) "POST" > To:  "https://CWDOMAIN.TLD/kobo/PERSONALAPI/v1/library/055ce5dd-9fe5-442e-a49b-8a754db0a6bf?BookSubId=416bfce4-e4ae-4730-8314-5857dece58a6" 
...
Feb 19 15:09:44 nickel: (  1826.474 @ 0x2571038 / packetdump.debug) 	---------------------- BODY --------------------------- 
Feb 19 15:09:44 nickel: (  1826.474 @ 0x2571038 / packetdump.debug) "" 
Feb 19 15:09:44 nickel: (  1826.474 @ 0x2571038 / packetdump.debug) -------------------------- END OF REQUEST --------------------------- 
Feb 19 15:09:44 nickel: (  1826.571 @ 0x2571038 / packetdump.warning) "https://CWDOMAIN.TLD/kobo/PERSONALAPI/v1/library/055ce5dd-9fe5-442e-a49b-8a754db0a6bf?BookSubId=416bfce4-e4ae-4730-8314-5857dece58a6" => "Error downloading https://CWDOMAIN.TLD/kobo/PERSONALAPI/v1/library/055ce5dd-9fe5-442e-a49b-8a754db0a6bf?BookSubId=416bfce4-e4ae-4730-8314-5857dece58a6 - server replied: METHOD NOT ALLOWED" 
Feb 19 15:09:44 nickel: (  1826.572 @ 0x2571038 / packetdump.warning) HTTP Status Code: 405 
Feb 19 15:09:44 nickel: (  1826.572 @ 0x2571038 / packetdump.warning) Error: 202

By adding the POST method to the /v1/library/ route, Calibre-Web correctly redirects the request generated by the "Read with Kobo Plus" button via the store on-device along with similar requests generated the addition of new notebooks.

[vahtos]

@formed2forge I was going to submit this PR until I saw yours. I saw your edit here, have you tried creating a new notebook and syncing again? The POST might only be required on new notebook syncing/creation?

[formed2forge]

@formed2forge I was going to submit this PR until I saw yours. I saw your edit here, have you tried creating a new notebook and syncing again? The POST might only be required on new notebook syncing/creation?

Creating a new notebook and syncing again continues to work on a device that is already synced from my initial tests.

My theory is that there is something that is getting communicated in the initial transfer of notebooks that allows for them to subsequently work with calibre-web's forwarding of requests. (This might be the one-time 'activation' that the software references when a compatible pen has been detected.) I'm in the midst of testing this and I have header and packet dumps to sift through to try to determine what's being sent and received and how so we can figure out how to direct/redirect the flow of traffic to allow for both the initial sync of notebooks to happen as well as the subsequent syncs.

[formed2forge]

@formed2forge I was going to submit this PR until I saw yours. I saw your edit here, have you tried creating a new notebook and syncing again? The POST might only be required on new notebook syncing/creation?

Looks like it's also used to apply Kobo Plus titles to user accounts. I've opened the PR back up because it appears to solve a couple of issues at this point.